Background: Angiotensin-converting enzyme (ACE) inhibitors are well established as long-term antihypertensives and have also been proved useful in hypertensive emergencies. Therefore, we investigated whether intraoperative i.v. enalaprilat may reduce the incidence of perioperative hypertensive reactions in coronary artery bypass grafting (CABG).
Methods: Thirty-eight male patients chronically treated for arterial hypertension and scheduled for CABG randomly and double-blindly received either enalaprilat 30 micrograms.kg-1 or NaCl 0.9% at the time of skin incision. Intraoperatively, increases of mean arterial pressure (MAP) > 85 mmHg or > 80 mmHg during cardiopulmonary bypass (CPB) were treated by an urapidil bolus. The total intraoperative amount of urapidil was documented for both groups. Systemic and pulmonary hemodynamics as well as the plasma levels of epinephrine, norepinephrine, arginine vasopressin and renin were measured intraoperatively and up to 2 h after admission to the intensive care unit.
Results: Mean arterial pressure, cardiac index and systemic vascular resistance did not differ between the enalaprilat and the control group. Renin plasma levels significantly increased after infusion of enalaprilat and did not change in the placebo group. Catecholamine and arginine vasopressin plasma levels increased significantly during CPB and remained high in the postoperative period without any intergroup difference. The same amount of urapidil had to be given in the two groups to maintain MAP below the defined limit.
Conclusion: We conclude that infusing 30 micrograms.kg-1 enalaprilat in patients chronically treated for arterial hypertension does not prevent hypertensive reactions during CABG.